I've also heard that (at least in Mexican slang) "buena onda" can mean that a person has good luck or that a situation is really fortunate (El carro le costo' a Jamie menos que pensaba, que buena onda.")

The phrase can also be used in the negative to mean bad luck or a person who never does good things for others (Pablo nunca quiere venir con nosotros. No tiene buena onda).